| 摘要 |
PURPOSE:To obtain excellent SNR characteristics extending over a wide temperature range by using a Wheatstone bridge circuit by a thermistor as a temperature compensation circuit in an avalanche photodiode (APD) bias method. CONSTITUTION:An output from a Wheatstone bridge consisting of resistors 14, 15, 16 and a thermistor 13 is input to a voltage adding circuit section 9 through a differential buffer amplifier 12 in a temperature compensation voltage generating circuit section 11, and the voltage is added to the output voltage from a constant-voltage generating circuit section 10. An output from the voltage adding circuit 9 is applied to a high-voltage generating circuit 7 as control voltage. Accordingly, the multiplication factor of an APD can be controlled optimally extending over a wide temperature range by a simple circuit, and a large effect is displayed when a photo-receiver is operated at a position where an ambient temperature remarkably changes. |
